TX3927 has three channel timer of which only channel 0 is used to
implement a clocksource -- however, clocksource code whould also need to be
changed since it's now jiffy-based and HRT doesn't tolerate this -- of course,
if anybody still cared about this boards

arch/mips/philips/pnx8550/common/time.c: mips_timer_ack = timer_ack;

Here we have a case of a vendor abusing the count/compare register and
also adding 3 more of them. One pair can be used for clockevents, the other
for clocksource (its compare reg. being programmed to all ones).